From wide-eyed recruits to the most grizzled veterans, the urge to abandon a fitness plan has plagued us all. Maybe your battle is staying in those dreaded formation runs or an old injury that threatens to sap hope of recovering — maybe it's just sticking with a new diet.

However you'regrappling with giving up, three new books offerinspiration to help keep your body and brain in the game.

Heartbreak to health

The fast-paced memoir "Running on Empty" covers lots of ground, from Marshall Ulrich's struggle with heartbreak and bad health to his makeover into one of the world's toughest athletes.

When his wife was dying of breast cancer in 1980, his blood pressure soared and he began to worry about his own mortality. He was only 29. His doctor and his brother told him to start exercising. He put on a pair of Converse sneakers and ran.

Among his feats: He finished the Badwater Ultramarathon, a 135-mile summer run across Death Valley, 17 times; climbed the highest mountain on each of the seven continents; and completed a transcontinental run of the U.S. when he was 57 (70 miles a day). His advice:

Keep pushing. Everyone wants to quit sometimes, he writes. "New obstacles will arise, but even when everything aches and you think you have nothing left, you do."

Keep it interesting. Try new things and set new goals. Running in races and searching for new summits kept him challenged.

Fitness highs and lows

Physician Vonda Wright's "Guide to Thrive" is part workbook and part coach. She recommends people develop a vision for health goals, write them down and track them.

Wright is an orthopedic surgeon who specializes in sports medicine and is director of the performance and research initiative for master athletes at the University of Pittsburgh.

"For years people have talked about the runner's high, but there are many forms of high-intensity exercise that produce the same feeling and other brain pathways are also stimulated by exercise," she says. Her tips:

Get a game plan. "Create a vision of what you want your health to look like."

Take action. She divides the plans into two-month sections. "We start at zero and do a day-by-day exercise and nutrition plan," she says.

Develop a new attitude. "Investment is not just about our bodies, it's also building bliss."

Keeping the faith

Struggling with shedding weight after the birth of her fourth child, Vicki Heath faced a crisis of confidence that had never been a problem in her previous pregnancies.

"I was becoming convinced I would never lose the weight," she writes in her new book, "Don't Quit, Get Fit: Overcoming the Four Fitness Killers."

A pastor's wife, she's long drawn spiritual inspiration from the Good Book but was surprised to find practical wisdom when she joined a weight-loss group dubbed "First Place 4 Health."

Nearly 20 years later, she's associate national director for the faith-based fitness group, a certified fitness instructor for the American Council on Exercise, a certified life coach and wellness coordinator for her church. Her tips:

Get honest. "Stop lying to yourself," she writes. "It is not too cold, it is not too hot, and your trainer does not hate you."

Identify the obstacles. These could be people, situations, bad habits. Next: "Stop complaining about the obstacles and start figuring out your next move."